[Expo-tech] Validation of links to survex files within drawings

[Philip Sargent (Gmail)]

New check for whether the reference to a survex file within a drawing file
(xml) is valid or not. All working online now:
http://expo.survex.com/xmlvalid.html
There are about a dozen where I can't work out which survex file is meant
but where the link is broken. So those drawing files need downloading and
correcting.

This one has live clickable URL links to the survex and drawings files to
make it easier for you to check what needs to be fixed.

Philip